All patients developing non-A, non-B hepatitis following open heart surgery will be followed with serial studies of ALT to determine the incidence of chronic liver disease and to compare this incidence with those having type B hepatitis. Liver biopsy will be obtained when the ALT is elevated for more than six months and then again at one and three years. Biopsy material will be obtained for fluorescent and EM studies, as well as light microscopy with multiple stains.